In recent times, the use of artificial stone materials for kitchen counter-tops, basins, tubs, and other fixtures has become very popular with contractors and property owners alike. These materials have the look of granite, marble and other expensive stone materials, but are less costly to fabricate and shape. These artificial stone materials usually comprise acrylic and acrylic/alumina trihydrate (Wilsonart®, Gibraltar®, SSVTM, DuPont Corian®), and are also known in the trade as solid surface materials.
In the manufacture of bowls, tubs, counter-tops, and basins of artificial stone-like materials, some manufacturers laminate or chemically weld multiple pieces of solid surface sheet stock together, and then machine the pieces to the desired shape. Some manufacturers mold solid surface material using two-piece (male/female) molds to create a basic form, and then cut and splice pieces to the deformed shape to achieve the depth and size that they ultimately desire. These methods require more labor and machinery to finish the surfaces, such as sanding the laminated or welded item, and therefore are more time, labor, and material intensive. The intensive nature of these artificial materials has kept the cost of the end products high.
The present invention features a low-cost, thermoforming process that is used to make three-dimensional solid surface bowls, shower pans, trays, kitchen countertops, and basins. The inventors have discovered that thermoforming is a cost effective method for overcoming the prior art manufacturing limitations of these materials. The inventive process uses a flat, rigid sheet of solid surface product that is heated to a uniform temperature to make it malleable. The material is then placed over a female or male mold and formed to a predetermined shape utilizing vacuum. The heated material is allowed to conform to the mold shape without substantial restraint, until most of the desired deformity is achieved. At that point, movement of the material becomes restricted; the balance of the desired deformity is achieved through stretching. The manufactured component is then allowed to cool in its restrained position, until rigid.
This procedure produces a flange, which provides a point at which, for example, the bowl/shower pan can subsequently be chemically welded in either a convex or concave position. After cooling, the material is removed from the mold and chemically welded to a countertop or curb assembly, in either a horizontal or a vertical plane. A supporting plate is welded at the desired drain location. A drain hole is then machined at the drain location to accommodate the drain hardware.
The inventive process allows formation of a shower base, sink, bowl, or other fixture in one piece, which can retain its shape without losing its strength and integrity. Most particularly in the case of a shower base or tub, further strengthening can be achieved using polyurethane foam. The polyurethane foam can be poured or sprayed onto the solid surface material.
The inventive method is unique in that no other current process can fabricate solid surface fixtures in one piece using a vacuum and producing a flanged, seamless cost efficient fixture.